The art of numerical control of machine tools has been very highly developed in recent years because of the many advantages accruing therefrom as compared with conventional methods of machining. Some of the advantages of numerical control are greater accuracy, higher production rates, quality improvement, less set-up time, and less operator skill required.
As is well known, the basis for measuring movements on numerically controlled machine tools is a Cartesian coordinate system consisting of three mutually orthogonal axes passing through a common origin point. Numerical control systems are of two types, the point to point system and the continuous path system. In the point to point system a machine tool has to perform operations at certain points as, for example, the control of a drill press wherein the drill is set into the work as a certain point and to a specified depth point, is then extracted and brought to a different position for a further drilling operation. In the continuous path system, the machining task is continuous and will involve two or three directional movements simultaneously as, for example, in contour milling or lathe work. The point to point system is relatively less complex than the continuous path system wherein inudstrial application necessitates the use of computers to aid in programming the machining operations.
Although persons can be trained in numerical control directly on machines specifically set up for this purpose, such machines and their requisite equipment are extremely complex and expensive, so much so as to be outside the normal reach of many institutions who otherwise are charged with the responsibility of training students for industrial positions.